Page 43 - EngineerIT November 2021

RADIO COMMUNICATION

used to trigger the loading of a hop table initiated by the BBIC. The
hop table loading should be completed before the hopping signal
edge after the channel setup signal falling edge, and then PLL starts
tuning to this frequency at the same hop edge and becomes ready
for the next hop frame signaled by the next hop edge. Tables A and
B operate in a ping pong mode so that, after loading is complete, FH
operates on the frequency of one table while the frequency of the
other table is being tuned.
Figure 10 presents the transmit frequency vs. time output
with dynamic table loading for four entries per load and eight
entries per load. The transmit input has four frames at 0 kHz,
–100 kHz, –200 kHz, and –300 kHz frequency, and it is fed to the
ADRV9002 by looping the frames continuously. It is also fully
aligned and synchronised with hop frames so that the 0 kHz input
frame aligns with 3.1 GHz LO. During FH, when LO changes to the
next frequency, the transmit input frequency also changes to the
Figure 9: An example of dynamic table loading with one frequency per table next frequency.
using PLL mux mode. Tables A and B are dynamically loaded while performing FH (for
simplicity and easy observation, the table content does not change
An example of a dynamic table loading with only one frequency from load to load). For four entries per load, we expect to see
per hop table A and B is described in Figure 9. This is an extreme case four consecutive transmit output frames at 3.1 GHz and then four
that allows users to change the hop frequency for every frame on- consecutive frames at 3.1004 GHz, and the same pattern repeats
the-fly. PLL mux mode is utilised in this example. As shown in figure again and again. For eight entries per load, we expect to see four
8, both the rising and falling edge of the hop signal define the timing consecutive transmit output frames at 3.1 GHz, four consecutive
boundaries of a hop frame, each consisting of a transition time and a frames at 3.1004 GHz, four consecutive frames at 3.1008 Hz, and
dwell time as mentioned earlier. The channel setup signal rising edge four consecutive frames at 3.1012 GHz, and the same pattern repeats
defines the type of hop frame that follows a one frame delay (this again and again. The transmit output shown in Figure 8 proves that
delay is necessary for PLL mux mode). the dynamic table loading works as expected.
Note that the channel setup signal could stand for either the
transmit setup signal or receive setup signal. Figure 9 shows a Channel diversity vs. channel multiplexing using dual channels
simplified version of the signal. Because TDD operation involves As shown in Figure 2, the ADRV9002 supports dual transmit and
both transmit and receive, users need to configure both the transmit receive channels. FH can be applied on both channels to achieve
setup signal and receive setup signal separately. In addition to either channel diversity or channel multiplexing.
indicating the hop frame type, the channel setup signal can also be For diversity, both channels are hopping simultaneously by using

Figure 10: A comparison of dynamic table loading with four entries per loading and eight entries per loading.

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